The present invention relates to data entry devices for computers, and more particularly, to a hand held device which can selectively operate to move a cursor on a CRT, enter textual or graphic information via optical scanning, or enter coordinate information based on relative positioning of the device with respect to an underlying digitizer pad.
Hand held mouse devices are well known which are manually movable over a desk top to position a cursor on the screen of a personal computer. Typically they incorporate track balls or other surface engaging means which rotate disk encoders to generate positional data. See for example U.S. Pat. No. Re. 32,633 of Hovey et al. granted Mar. 29, 1988 and assigned to Apple Computer, Inc.
Digitizer systems has also been in use with personal computers for many years, particularly for digitizing and recording graphic data such as lines and curves from a work sheet by tracing over the same, usually with a puck incorporating a cross-hair which facilitates accurate sighting. Typically the work sheet is laid over a digitizing pad having embedded therein conductor grids which inductively cooperate with a flux producing element in the puck. See for example U.S. Pat. No. 4,689,448 of Synder et al. granted Aug. 25, 1987 and assigned to Summagraphics Corporation.
More recently hand held optical scanners have been commercially available for entering text directly into a personal computer. Light from a hand held device is reflected off the page to create an image on a charge coupled device (CCD). In some cases, the operator programs the device to recognize a particular character size and font. The device is then manually slid along each line of text in order to enter the information character by character. Processing circuitry connected to the CCD provides ASCII signals to the personal computer representative of each of the characters scanned. Some of these hand held optical scanners are based on a pattern recognition approach. However the accuracy of such hand held optical text entry devices is marginal, partly due to the fact that sighting is difficult and they do not incorporate position sensing means. Furthermore, they are not capable of entering non-textural graphic information directly into a computer.
Presently a user must purchase a separate mouse, optical scanner and digitizing system and connect the same to his or her personal computer in order to have all of the foregoing capabilities available for a common application. Such capabilities are rapidly becoming essential for many financial, engineering and scientific programs. Apart from the substantial expense, the multiple devices lead to physical clutter on the desk top, where space is already at a premium, especially taking into consideration the fact that the user already has a conventional keyboard input device. Multiple input devices have duplicate power supplies and serializers. Furthermore, the convenient use of a plurality of such data entry devices with a single personal computer can be hampered by physical interconnection, data entry port and interface limitations. Several card slots are required for multiple input devices, but more demanding are the software implications of multiple input devices which must compete for the single data stream input to an application. The original architecture of the personal computer was not designed to support this diversity of input devices. In many cases it is the last device loaded that works, locking out all other devices. In some cases, dissimilar types of input cannot even reside in the same machine because of memory conflicts. There is no logical control system to provide pre-processing necessary to satisfy the limited resource managers resident in the typical personal computer hardware and software.